TABLE 3.

Bader charge analysis and N1 protonation status for selected purine analogs

Molecule	Xa	X charge	Ya	Y charge	N1(H)
Inosine	=O	−1.173			N1H
6-Mercaptopurine riboside	-S-	+0.164	H	0.020	N1
	=S	−0.231			N1H
6-Methylmercaptopurine riboside	-S-	+0.122	CH3	0.005	N1
6-Chloroguanosine	-Cl	−0.197			N1
Adenosine	-N-	−1.090	H	0.450	N1

^a X indicates the non-ring atom connected to C6. Y indicates the atom(s) connected to X, if any.